1. Field of the Invention
The present invention relates to a motor for spinning a disk-shaped storage medium and to a disk drive mounted with the motor.
2. Description of the Related Art
An exemplary known motor is described in JP 2006194400 A and its counterpart U.S. patent publication No. US 2006/0158052 A1. In the motor, magnetic attraction between a rotor magnet and a yoke made of magnetic material exerts a force in the opposite direction to the direction in which the rotor floats. That is, the magnetic attraction generated between the rotor magnet and the yoke is a reaction force to the force that makes the rotor float.
If the yoke is attached obliquely relative to the rotor magnet, the magnetic attraction is uneven in the circumferential direction of the rotor magnet, thus making rotation of the rotor unstable. Particularly, a spindle motor used for spinning a disk-shaped storage medium (hereinafter, simply referred to as a disk) in conjunction with a magnetic head may encounter the following problem. In the spindle motor, a gap between the disk and the magnetic head is very small. Therefore, instable rotation of the rotor may cause the disk to come into contact with the magnetic head. In order to prevent this, the yoke needs to be attached to the base without being inclined relative to the rotor magnet.
In addition, the recent price decline on disk drives has intensified demands for price reduction for motors to be mounted to the disk drives.